let me try and explain it in the best way that I can, based on my own experience and theoretical knowledge.

first, breathing is essential for life, so therefore our biological "alarm" system is very sensetive and takes a very large margin. this is why we can experience shortness of breath, even when there is only a mild impairment of our respiratory system and we have a good respiratory reserve.

the breathing center in our brain is very sensetive to the absolute level of CO2 in our blood and also to changes in it. kids that have contests of breath holding learn to "hyperventilate" before and then their CO2 levels go down and they can hold their breath longer. but if you hyperventilate too much you will start feeling dizzy and tingling in your extremities, the reason for that is a change in the acidity of your blood and a decrease in the level of calcium.

if you hold your breath, your level of CO2 will start rising and reach a level in which your respiratory drive will be so high that you will be unable to keep on holding your breath any more. this senseation is a horrible feeling of suffocation. and that is why if you can't breath enough to correct it you may feel like you are about to die.

this is different from one person to the other. some people are extremely sensetive to very small changes in their CO2 level and others can tolerate much higher levels. also, people that have chornically high levels of CO2 (such as patients with COPD) will become less sensetive to it.


at this stage of CO2 retention you may feel very agitated,

if the CO2 levels keep on going up, you will start to feel more and more solmnolent. this may almost be a feeling of euphoria, at some point. and this is really dangerous, because then you just gradually sink.

if your CO2 levels are constantly higher then your normal, you may just feel totally wiped out, physically and mentally. you may also experience morning head aches, as when you sleep your CO2 retention becomes worse.

the O2 levels may be slightly decreased or even near normal, as the gas exchange of oxygen is dependent on many other factors, and you need much less ventilation in order to keep it intact.

all the consequences of CO2 retention are basically reversible once the level is corrected. as opposed to significant hypoxemia, which can easily lead to irreversible brain damage, within a few minutes.

the use of oxygen, can sometimes make the CO2 retention worse, due to complex processes, and therefor most neuromuscular pulmonologists do not recomend its use.

a respirator, allows the respiratory muscles to rest (as obviously you can't let them rest, like you would your arms or legs, by stopping to breath for a while). sometimes no more then 15 minutes are required and sometimes an entire day. sometimes every few hours and sometimes no more then once a week, all depends on the various factors that affect the activity of this illness.

I have learned, the hard way, that even excellent pulmonologists, with a very good understanding of neuromuscular disease, can be totally ignorant when it comes to non-invasive respiratory support.

and it was quite funny, because at one point I had a pulmonologist that had a good understanding in neuromuscular disease and another that had no understanding in that, but had a good understanding of NIV. and none was interested in communicating with the other. at some point I realized that this just doesn't work and eventually found one that understands both.

I hope this has been of some help,

as I have said neuromuscular pulmonology is very complicated and in a fluctative illness like MG even more, and my knowledge in that is limited.

alice

Thanks, Alice. It's true that metabolism, breathing, electrolytes and fluid issues can be incredibly complex. HOWEVER, someone who is a good neuro or a good pulmy can identify and treat a patient with those problems in their respective roles as doctors. It's when they don't that I go berserk. Or when they think that an MGer (me) who can't move or breathe and has O2 sats at 80% and whose arterial blood gas shows "hyperventilation" but they pass it all off as anxiety when the person is calm as a cucumber that I simply don't know why they are doctors at all.

This is a small, paperback book that has helped me a lot since 2000. It's Mosby's Fluid, Electrolyte and Acid-Base Balance (pocket guide series). It may be too much for some people but the nerds out there will love it.

And, no, I'm not saying to play doctor! But it helps to understand this stuff.

And understanding that electrolytes are part of this whole MG mess is important too.

Annie

Hi Alice,

Wow, that's a lot of great information!!

One of my first symptoms when I was really, really sick was severe mental confusion and memory problems. I went from being a grad student in math to not being able to follow a recipe, or remember my zip code. So, when you mentioned co2 retention my little internet ears perked up.

I hope you don't mind but I have some more questions. Some might seem kind of random or way off the mark because I am completely in the dark about how this stuff works. And I know from good old google that it is not easy to understand!! Okay, here goes:

1. Am I right or am I wrong in thinking that co2 retention could cause mental fog and memory problems?

2. Hyperventilation and co2 retention looks the same - is that right? Or rather hyperventilation is co2 retention. Do I have that right?

3. Assuming that I'm right on #2, you mentioned that hyperventilation can cause acidity in the blood. I was told last spring that my blood tests showed high lactic acid and high pyruvic acid and a high ratio of both (can't remember now which way the ratio is set up l to p or p:l). Could that be related to co2 retention or is that more of an anaerobic cell functioning thing?

4. What exactly is a respirator? Does it run on the same principal as a CPAP in that it raises the pressure of the air? I have a CPAP which I use which makes breathing in easier but breathing out harder. It really helps with the oxysats but sometimes, especially when I'm generally feeling like I have breathing difficulties I'll wake up feeling like a train hit me. I'm thinking about going in and begging for a biPAP. Anyway, I'm curious about your respirator.

5. I think I already know the answer to this one but I was thinking how nice it would be if there were the equivalent of an oximeter for co2. There isn't though, right? How come it's harder to measure co2 than it is oxygen?

Alice, if you're not comforable answering all these questions I TOTALLY understand. Also you're probably worn out. But if you do want to answer them that would be great because I am DYING of curiousity.

Thank you!!!!

Ally

Ally, you had high pyruvate and lactic acid? Are you sure you don't have a mitochondrial myopathy/cytopathy?

http://www.mitochondrial.net/showabs...tase+increased

http://emedicine.medscape.com/article/768159-overview

I'm not Alice but I can answer a couple questions.

With MG, there is a progression (often but not always) of what happens. And I'm paraphrasing from a book on MG (and my own experience). O2 sats drop lower late in the game with MG. They may drop a bit at first. Then there is hyperventilation on arterial blood gases. By this time, someone with MG is already in trouble. The step after that is CO2 retention, which is BAD. You need help immediately at that point.

You can go straight from "ok" to CO2 retention too. There's no predictable way that your respiration will go south. And, yes, too much CO2/not enough oxygen seriously affects both the heart and brain.

Ask your pulmy about the BiPap, or whomever ordered it.

There just isn't an equivalent of an oximeter for CO2. You can read this:

http://www.fpnotebook.com/Lung/Lab/OxygnStrtn.htm

You really have to go by how you are feeling and an oximeter if you have one. When in doubt, go in!!!

Seriously, has anyone done a muscle biopsy for you?

Annie

Annie,
I am not alice either, but just use this name because I am a bit of a coward, and prefer not to mix my professional life with MG life. (although they do crossover sometimes).

I am pretty bad, though at "playing" someone else, and couldn't even be a good scarecrow in the "wizard of Oz" play in fourth grade.

although, a few neuros made me realize what excellent dramatic skills I actually have, and what an amazing ability to appear as if I was seriously ill and convince the head of the ICU to admit me there.

and after my first (And then I thougt last) hospitalization I wrote my colleagues a letter to thank them for their support, when I felt as if I was in "alice in wonderland's world", so being in "MG world" is being alice for me.

Ally,

the answer to your questions-

1. you are right, CO2 retention can cause transient cognitive problems, and also feel like depression.

2. hyperventilation is in fact the opposite of CO2 retention, but they can appear the same, to the unexperienced. hyperventilation means breathing fast and getting more gas exchange (more ventilation) which leads to low levels of CO2. in CO2 retention-you have high levels of CO2 and you have a relatively rapid and shallow breathing because your body is trying to get rid of the CO2.
what may happen is that you "overshoot" and actually get your CO2 levels below normal. you can compare this to a driver who's steering wheel goes left and then a less experienced driver will break all the way to the right.

and as Annie says, this may appear as if you are hyperventilating, eg breathing fast because of anxiety etc. and not that you have an underlying problem.

when your weakness becomes more severe, you are not able to do that anymore and then your breathing becomes slow and shallow, and your CO2 levels rise.

3. as Annie said, if those results are real (because they could be the result of putting a tourniquet and applying pressure that leads to ischemia=not enought blood reaching your arm), then this would highly suggest some metabolic abnormality such as mitochondrial myopathy.

4. a respirator, is a machine that "breathes" for you. a CPAP is more of a support of your own breathing, but the problem is that it has the same pressure all the time (continous positive airway pressure), and that may be too low for getting air in, and too high for getting it out. (as you have to exhale against some pressure).
Bipap is bilevle airway pressure, which gives you a higher pressure when breathing in and a lower pressure when breathing out. so even if you are totally paralyzed it will do the work of breathing for you.

5. there is an equivalent of pulseox. that measures CO2 and it is called a capnometer. it is very expensive and many pulmonologists don't trust it too much (because you have to blow into it and know how to do it, normally it is attached to a respirator in the ICU, but can't be attached to a non-invasive respirator). I have one and I find it very reliable, most of the time.

alice

That's too funny because my real name IS Alice. Seriously! I started going by Ally in college.

Thank you, Faux Alice , for answering my questions. I really appreciate it!!! And Annie too!!

Good to get the hyperventillation/co2 retention ideas cleared up. What you described (Alice) about overshooting the mark and getting low co2 happened to me a few months ago when I went to the ER for breathing problems. By the time they got around to drawing blood hours later my co2 was low and I got a lecture on hyperventillating. Fortunately my friends piped in to say, "No, no, she was gray in the face, she really couldn't breathe".

As for the metabolic disease, I have my doubts about whether the blood was drawn correctly. It was done by the awful neuro who said all the wrong things about mg. I was told later that he thinks everyone has a metabolic problem and when I called the metabolic clinic about getting a muscle biopsy they said that they didn't take his patients because he was always making mistakes. Still, I keep it in my back pocket.

I had the night from he** last night, really struggling to breathe. It was awful and horrific. So on Monday I'm calling the neuro to beg for mestinon and I'm calling my sleep doctor to beg for a bipap. I wanted to hold out on the mestinon until I got the pulmonary and emg tests done the third week in November but I just can't take it anymore.

Thanks again both Alice and Annie!!!!!!!!

Ally

This is what I was talking about. Here is a quote from the book Neuromuscular Junction Disorders: Diagnosis and Treatment, by Dr. Meriggioli, Dr. Howard and Dr. Harper:


And when they do the arterial blood gas, like they did with me during my crisis, while you have oxygen on, the readings are completely inaccurate!

I was decompensating big time. 2/5 muscle strength and O2 sats dipping into the 70's. MIP average of -24. I was "fine" though, right? They didn't really need to put me in the ICU where my breathing could be monitored. They didn't really need to give me more than oxygen. And so what if I waited four days for any other treatment? I must've just been anxious.

Ally/Alice and Alice/?, this is a good discussion. I know that it's complicated for a lot of people. Metabolic acidosis and respiratory alkalosis? It makes even doctors' heads spin. And the fluid issues I went through with diabetes insipidus going undiagnosed . . . I swear they couldn't figure it out if it was pointed out.

My real nickname is Annie.

Annie

Ho-Ly Cow!!!! I can't believe they sent you home in that kind of shape!!!!

You are right Annie/Annie , this is very complicated stuff. After I read your last post I had to look up the word "decompensate" which shows you just how elementary my understanding is.

I have the book on mg written by Dr. Kaminski (actually I have two copies - want one?!? PM me if you do). I understand maybe 1/100th of it but I think I'll go back and read up on the respiratory parts and see if I can glean anything. If there are respiratory parts that is, I don't remember.

Ally

Annie,

you are right that in order to start having gas-exchange problems, you need to have very significant respiratory muscle weakness.

there is also a difference between having acute respiratory muscle weakness and chronic respiratory muscle weakness, in which you body gradually adjusts. its just like the difference between having a Hgb of 6.0 due to nutritional iron def., which gradually develops over time or having a Hgb. of 6.0 due to acute blood loss, or even acute hemolysis (where there are no hemodynamic changes).

when I was in crisis, 4 years ago, my MIP was -20, but my "baseline" MIP at that time was -70. so this was an abrupt change.
now my baseline MIP is around -35, and can go up to -40 on very good days or down to -20 on less good times, and I feel really ill, only when I am nearly paralyzed.

if I have a few really good days (which can occassionaly happen), I feel horrible when I go back to my "normal" baseline. and get a terrible headache with a PCO2 of a bit over 40. but, then within a few days, I feel reasonably well, and may have a PCO2 of 50+, without experiencing significant shortness of breath, and just feeling a bit less focused.

your story about your crisis sounds horrific.
I have had some similar experiences, and just couldn't believe that this could happen in the 21st century, and it is very hard for me to convince my colleagues that it does. (and I can understand why, because I am not sure I would have believed it).

I have promised myself that I will do everything that I possibly can to change this.

are you ready to help me in that?

alice

didn't realize that Ally was Alice.

but, I think you can relate to my alice in wonderland experiences any how.

sorry to hear about last night.

I can't believe it, you are not even getting mestinon!

and I thought they were trying to see the "natural history" of this illness on me!

wow, if I didn't have mestinon and neostigmine, I would be pretty much bed-bound and connected to my respirator most of the time.

did they do a sleep study measuring your CO2 levels, and did they see how you breath with the respirator as well?

probably your answer is going to be no. but, it should be yes.

good thing they didn't go ahead and do a muscle biopsy, when you are having such respiratory problems.

I was stupid enough to eventually agree to have one done, and it made me go down-hill fast.

well, at least I got a respirator "thanks" to that, and it also made me understand that insisting on working full time, was not very realistic any more.

but, you are sero-positive aren't you, so why search for some extremely rare condition, that you most likely don't have?

as one of my teacher used to say, when you do tests, without knowing what you are looking for, you are going to end up having very "interesting" results.

alice